[PATCH 3.12 48/62] x86-64, build: Always pass in -mno-sse

Greg Kroah-Hartman
2013-12-10T08:11:02Z

From: "H. Peter Anvin" <hpa@linux.intel.com>

commit 5551a34e5aeab868f8d37f70d8754868921b4ee5 upstream.

Always pass in the -mno-sse argument, regardless if
-preferred-stack-boundary is supported. We never want to generate SSE
instructions in the kernel unless we *really* know what we're doing.

According to H. J. Lu, any version of gcc new enough that we support
it at all should handle the -mno-sse option, so just add it
unconditionally.

Reported-by: Kevin B. Smith <kevin.b.smith@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: H. J. Lu <hjl.tools@gmail.com>
Link: http://lkml.kernel.org/n/tip-j21wzqv790q834n7yc6g80j1@git.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/Makefile | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -31,6 +31,9 @@ ifeq ($(CONFIG_X86_32),y)

KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return

+ # Don't autogenerate SSE instructions
+ KBUILD_CFLAGS += -mno-sse
+
# Never want PIC in a 32-bit kernel, prevent breakage with GCC built
# with nonstandard options
KBUILD_CFLAGS += -fno-pic
@@ -57,8 +60,11 @@ else
KBUILD_AFLAGS += -m64
KBUILD_CFLAGS += -m64

+ # Don't autogenerate SSE instructions
+ KBUILD_CFLAGS += -mno-sse
+
# Use -mpreferred-stack-boundary=3 if supported.
- KBUILD_CFLAGS += $(call cc-option,-mno-sse -mpreferred-stack-boundary=3)
+ KBUILD_CFLAGS += $(call cc-option,-mpreferred-stack-boundary=3)

# FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)